I think these units are really targeting two slightly different buyers. The Samsung is going for the buyer that wants a unit that is sleek, light, thin, more mobile, and not an iPad. The Transformer targets someone for who needs/wants the dock's capabilities. Someone who willing to put up with the slightly higher weight and bulk to get the docking and additional I/O capabilities.
I want the docking to allow easier use of creating data in business situations (emails, documents, spreadsheets, etc) and my photography hobby (view images and upload to a hard drive, etc). I view to the transformer as a netbook/tablet combination for creating content vs a standalone tablet which is more of a content consumption device.
FWIW, if I wanted something sleeker and lighter and more of an iPad killer I would wait and play with the Samsung 8.9. That unit is even lighter and thinner, and based on my experience with the iPad and Nook Color, the 8.9 screen may be the perfect size.
Jerry